This Subfamily contains the Green Pigeons, beautiful birds recognizable by their bright green or yellowish-green plumage and the exceptionally broad, fleshy soles to their feet. The wings are marked with one or two broad yellow bars and the upper plumage often mixed with maroon. The tail-feathers number fourteen and vary much in shape; the wings are long and pointed and the primaries differently shaped in different genera (vide Plate I.) ; the tarsus is stout and very short, the upper part well feathered.
The Subfamily extends throughout the tropical and subtropical regions of the Old World, five genera being found within the limits of. this work.
The division of the Subfamily into genera is one of: great difficulty, for the structure of the wing has been used as a generic character without a sufficient examination, so that in the result we find that at the present time certain genera, especially Dendrophasa (Osmotreron auct.), contains species and subspecies which in no way conform 'with the. diagnosis of the genus. At the same time the formation of the wing, when used in conjunction with other characters, such as the position of the ramphotheca, does seem to form a very valuable character, enabling one to work out "groups which seem both natural and convenient. I have had the advantage of working out this Family, Columbidae, with Mr. H. Robinson, who has himself been studying them and has given me his notes thereon. We are agreed that, in so far as Indian birds are concerned, the following key is as satisfactory as is possible at present.
Key to Genera.
A.Primaries strongly attenuated............ CROCOPUS, p. 180.
B.Primaries blunt or very slightly attenuated.
A.Third primary strongly scalloped.
a1. Ramphotheca remote from forehead………………Dendrophasa, p. 184.
b1. Ramphotheca reaching or nearly reaching forehead.
a2.Primaries slightly attenuated; third primary widely and deeply scalloped……….TRERON, p. 195.
b2. Primaries blunt third primary widely but shallowly scalloped.......BUTRERON, p. 197.
B.Third primary expanded and not scalloped…………….SPHENOCERCUS, p. 198.
* Very irregular in Myristicivora, in which the tail-feathers sometimes number 12 only,